This invention relates to acyclic machines, and more particularly to such machines utilizing a plurality of high current density field coils, such as superconducting field coils.
A coaxial disk stack acyclic machine is described in U.S. patent application Ser. No. 710,926, filed Aug. 2, 1976 by Jenkins, now U.S. Pat. No. 4,097,758, and assigned to the assignee of the instant application. In that application is disclosed a machine which utilizes a stack of coaxial disks to cut magnetic flux on both the radially-inner and radially-outer sides of a conventional field coil.
A multiple drum-type machine is disclosed in U.S. Pat. No. 3,579,005, issued May 18, 1971 to Noble. That machine includes multiple coaxial field coils and multiple coaxial drums. Liquid metal collectors are known in the prior art as exemplified in U.S. Pat. No. 4,027,184, issued on May 31, 1977 to Hurley and in U.S. patent application Ser. No. 876,570, filed Feb. 10, 1978 by the instant inventor, and U.S. Pat. No. 3,211,936, patented Oct. 12, 1965 to Harvey, all assigned to the assignee of the instant application.
A homopolar dynamoelectric machine using superconducting field coils is disclosed in U.S. Pat. No. 3,944,865, issued Mar. 16, 1976 to Jewitt. That patent discloses using two rotors of cylindrical drum form, one interior of the field coils and one exterior of the field coils to utilize the magnetic field of the superconducting coils.
In marine applications, strict limitations are imposed upon machine size and weight. In the invention disclosed herein, by utilizing high current density field coils a high density magnetic field can be created with the minimum physical size. By using a homopolar machine construction, the shielding iron of the machine is used simultaneously as armature conductors for the magnetic field. This combination of high current density field coil and homopolar construction enables minimizing physical size of a shielded machine. To achieve maximum output torque from such a construction requires maximum utilization of the high strength magnetic field generated by the high density current flow through the coils.
Accordingly, the primary object of the present invention is to maximize utilization of the high magnetic flux density available in a machine using high current density coils to provide a high power density, e.g. in horsepower per pound, machine. A further object is to minimize the Lorentz expulsion force applied to liquid metal in liquid metal current collectors of such a machine.